Nonalcoholic Fatty Liver Disease (NAFLD) & Nonalcoholic Steatohepatitis (NASH): Non-alcoholic fatty liver disease (NAFLD) is a condition characterized by too much fat built up and stored in liver cells. People who do not drink a lot and have fatty livers are considered to have NAFLD. Non-alcoholic steatohepatitis (NASH) is a condition in which excess fat in the liver cells cause inflammation and damage. It is an advanced form of NAFLD. NASH is differentiated from NAFLD when inflammation and scarring (cirrhosis) of the liver become present.